Effect of Polymer Structure on Membrane Morphology by Addition of 2-butoxyethanol

Flat sheet microfiltration membranes were prepared with polysulfone (PSF), polyethersulfone (PES), and polyphenylsulfone (PPS) by an immersion precipitation phase inversion method. In this method, dimethyl formamide (DMF) and polyvinylpyrrolidone (PVP) were used as a solvent and a wetting polymer additive, respectively. 2-butoxyethanol (BE) was used as a nonsolvent additive catalyst to form pore. The morphology of membranes was investigated by scanning electron microscopy and micropermporometer. The permeability of the membranes was evaluated with the flux of pure water. When the BE was added, the pore size of membranes became larger than blank membranes. The changes in the morphology of membrane due to the BE addition depend on polymer structure. All membranes have similar mean pore size and porosity. The mean pore sizes of PSF, PES, and PPS membranes were 0.282, 0.330 $0.308{\mu}m$, respectively. The porosities of PSF, PES and PPS membranes were 68.5, 66.1, 66.4%, respectively. However, the PPS membrane showed higher pore density on surface and narrower pore size distribution than PSF or PES membrane does. As a result, the pure water flux of PPS membrane ($357L/m^2\;hr$) was higher than that of PSF ($196L/m^2\;hr$) or PES membrane ($214L/m^2\;hr$).

2-butoxyethanol 첨가에 따른 고분자 구조가 분리막 구조에 미치는 영향

침지법을 이용한 상전이 공정으로 polysulfone (PSF), polyethersulfone (PES) and polyphenylsulfone (PPS)의 정밀여과 평막을 제조하였다. 용매로는 dimethyl formamide (DMF)를, 습윤제 고분자로는 polyvinylpyrrolidone (PVP)를 사용하였으며 pore 형성 촉매로 2-butoxyethanol (BE)을 사용하였다. 얻어진 분리막들은 SEM과 micro permporometer를 이용하여 morphology를 분석하였으며 순수투과도를 측정하여 분리막의 투과성능을 측정하였다. BE의 첨가를 통하여 분리막의 기공을 성장시킬 수 있었으며 고분자 구조에 따라 분리막의 morphology 변화를 관찰할 수 있었다. PSF, PES, PPS 분리막의 평균기공의 크기는 각각 0.282, 0.330, $0.308{\mu}m$이었으며 공극률은 68.5, 66.1, 66.4%로 유사한 값을 나타내었다. 그러나 PPS 분리막의 경우 PSF, PES 분리막에 비해 높은 기공 밀도와 좁은 기공 분포를 관찰할 수 있었다. 그 결과 PPS 분리막의 순수 투과 유량은 $357L/m^2\;hr$으로 PSF ($196L/m^2\;hr$)나 PES membrane ($214L/m^2\;hr$) 분리막에 비해 훨씬 증가함을 보였다.